Edinburgh gets its trams

In Edinburgh, there is enthusiasm about the introduction of the city’s tram service on 31 May. Writes David Shirres

This much is clear from Twitter and correspondence columns in the Scottish Press. As an example, an appeal for a thousand volunteers for a tram crowd exercise was fulfilled within 24 hours and massively over-subscribed.

However, there are also many who are not so enthusiastic and consider the trams to be an unnecessary waste of money. This is understandable as the project opened three years late, was almost £300 million over budget and delivered only 14.2 km of the original 18.5 km network as a result of a 2011 decision not to build the section from Newhaven and Leith to Edinburgh.

Background

In 2007, the Scottish Parliament voted to fund the tram project and authorised £490 million for a tram service between Newhaven and Edinburgh Airport which was to open in 2011. However the project ran into difficulties with almost twice the number of expected utility diversions and disputes with the infrastructure contractor. With these resulting in significant delays, the project team advised Edinburgh City Council in June 2010 that it was prepared to terminate the infrastructure contract should this be necessary.

The turning point for the project was the Council’s decision in November 2010 to support independent mediation. This led to talks being held the following March at which the mediator was successful in facilitating a mutually- agreed resolution. Shortly afterwards, the contractor re-mobilised staff at priority locations. A settlement agreement was signed in June 2010 which incorporated a revised budget of £776 million and a programme to deliver passenger services in summer 2014. So, whilst there are project lessons to be learnt up to the mediation, the project has been successful in keeping to time and cost since the revised agreement. Furthermore, its initial difficulties do not detract from the case for a tram network or the quality of its engineering.

Leaving the city

From its terminus in York Place, the tram runs through the city streets, including Princes Street, for 2.6 kilometres to an interchange at the new Haymarket station (issue 105 – July 2013). There are five tram stops in this section.

The track is the Rheda City system supplied by the German company RailOne. This has two concrete sleeper pads separated and located by an integral steel lattice-girder embedded in a poured concrete slab. The track sits on a 250mm-thick ground improvement slab which is designed to span a one metre void. In the city, black concrete is used for the final pour so the track blends into the city’s streets.

Ensuring that the tram system does not detract from Edinburgh’s status as a World Heritage City was a challenging task. To both meet this requirement and improve the quality of streets and open spaces, the Council produced a Design Manual which was used as a reference point for all planning consent applications.

On the streets

It was on and under the city’s streets that the project faced perhaps its greatest challenge – the diversion of utilities. This was undertaken under a Multi-Utilities Diversion Framework Agreement (MUDFA), the scope of which was based on information provided by the utilities. This contract was let in 2006 with the intention that utility work would be complete prior to commencement of the main works in 2008.

In the event, the difference between actual work and the original scope was 295 chambers instead of 190 and 46.5 km of ducts /pipes instead of 27.2 km. As a result, utility work continued into 2012 and, while it resulted in extra costs and delays, it did result in a significant improvement to the city’s infrastructure.

The extended utility work and tram works required an extensive programme of closures of the city’s main thoroughfares. The required diversions were planned on the basis of traffic modelling. Track work was also planned to minimise disruption with work cut into small sections of, typically, 40 metres. Nevertheless, this work inevitably involved extended periods of disruption.

The tram works also uncovered a number of archaeological finds. In Constitution Street in Leith, 390 graves were unearthed in a former graveyard dating between the late fifteenth and eighteenth centuries, and the remains of a sixteenth century leper hospital were discovered. Close to the airport, prehistoric and Dark Age settlements were found.

Of more recent vintage, an 80 metre long underground Second World War bunker was discovered at Haymarket. This had started life as a pulley room for Edinburgh’s nineteenth century cable powered trams. The modern tram system’s foundations were redesigned to preserve the structure of this bunker.

The railway corridor

The off-street section starts at the interchange stop at Haymarket station and then runs parallel to the Edinburgh to Glasgow railway for six kilometres, crossing it by two bridges. It goes around the back of Haymarket depot, passes Murrayfield stadium and makes use of a former guided busway. The route leaves the railway at Edinburgh Park where there is another interchange tram stop.

With its proximity to the railway, immunisation work was required to address Network Rail’s concerns that the tram’s 750V DC power supply might interfere with signalling equipment. The tram design also had to make passive provision for Network Rail’s electrification proposals.

The 55-metre-long low viaduct at Haymarket was built on the site of the Caledonian Ale House. This unfortunately had to be demolished to accommodate a tram station that sits on the viaduct. This is one of 12 bridges on the off-street section with a combined length of 566 metres – there is another 232-metre-long viaduct at Edinburgh Park station.

The Murrayfield tram stop is on raised ground at the back of Haymarket depot. Here, poor ground conditions required a combination of ground improvement work and the use of Leca LWA lightweight fill and a Tensar Geogrid wall system.

To the airport

From Edinburgh Park, the tram line crosses a dual carriage to the Gyle shopping centre after which there is an underpass under the A8 road. Just after this the line passes the Gogar tram depot whose construction was reported in issue 82 (August 2011). The route then goes over open country to its terminus at the airport.

Close to the depot is the planned Edinburgh Gateway station which will provide an interchange with the railway to Fife and Aberdeen. Work on this station, which is being built by Transport Scotland on behalf of the Scottish Government, is expected to start in September for completion in 2016 at a cost of around £30 million.

This section also involved significant construction challenges. The underpass under the A8 necessitated significant utility diversions including data cables for the nearby Royal Bank of Scotland headquarters complex.

The line’s passage through the Gogar landfill area required a reinforced earth batter which incorporated around 400 twelve-metre-long soil nails.

The design contract was awarded in 2005 to System Design Services, a joint venture between Halcrow and Parsons Brinckerhoff. Part of the requirement was the early identification of utility works, land purchase and traffic management.

The infrastructure construction works were undertaken under the INFRACO contract which also includes infrastructure maintenance. In 2008 this was awarded to BBS, a consortium of Bilfinger Berger and Siemens. BBS operated as a management contractor letting out packages which included the depot (Barr Construction), track (BAM Rail) and general civil engineering (Raynesway, Graham, McKenzie Construction, Crummock, Farrans Construction and McKean Group).

Once the mediation settlement of 2011 was in place, Turner and Townsend, which had previously worked on the Croydon, Dublin and Nottingham tram systems, were appointed to assist the City of Edinburgh Council in the project management of the works.

The last contract to be awarded was to Parkeon for the supply and maintenance of the ticketing machines, platform validators and hand-held terminals with back office software support. These will accept Lothian Buses’ Ridacards and ITSO cards.

At the airport, the required road alterations involved the diversion of the Gogarburn river, 310 metres of piled retaining wall, road re- location including a new 32 metre bridge and provision of a signal controlled level crossing.

Infrastructure contracts

As with any large scale infrastructure project, a number of companies were involved. The first works contract to be let in 2006 was the MUDFA contract – awarded to Alfred McAlpine Infrastructure Services which were subsequently taken over by Carillion. Following the 2011 mediation settlement, utility work was awarded to McNicholas.

The design contract was awarded in 2005 to System Design Services, a joint venture between Halcrow and Parsons Brinckerhoff. Part of the requirement was the early identification of utility works, land purchase and traffic management.

The infrastructure construction works were undertaken under the INFRACO contract which also includes infrastructure maintenance. In 2008 this was awarded to BBS, a consortium of Bilfinger Berger and Siemens. BBS operated as a management contractor letting out packages which included the depot (Barr Construction), track (BAM Rail) and general civil engineering (Raynesway, Graham, McKenzie Construction, Crummock, Farrans Construction and McKean Group).

Once the mediation settlement of 2011 was in place, Turner and Townsend, which had previously worked on the Croydon, Dublin and Nottingham tram systems, were appointed to assist the City of Edinburgh Council in the project management of the works.

The last contract to be awarded was to Parkeon for the supply and maintenance of the ticketing machines, platform validators and hand-held terminals with back office software support. These will accept Lothian Buses’ Ridacards and ITSO cards.

The trams

The contract for the supply and maintenance (for 30 years) of 27 trams was let to Construcciones y Auxilar de Ferrocarriles (CAF) in 2008. These trams were built at the CAF factory in Irun, northern Spain, and were delivered between 2010 and 2012 in accordance with the original project programme. Since then, they have been subject to a CAF-specified conservation maintenance regime which included the requirement to move each tram once a month. A 200-metre section of the route adjacent to the depot opened in 2011, enabling the trams to be tested on delivery, some driver training and the required monthly movement.

At 42.9 metres, these are the longest trams in the UK and have been designed to negotiate Edinburgh’s tight curves and steep gradients. They are 2.65 metres wide, weigh 56 tonnes and consist of seven articulated modules. Four of the modules have a single bogie. The three other modules have no wheels and are suspended between adjacent bogie modules.

The trams are supplied by a 750V DC overhead catenary and have twelve 80kW traction motors on three powered bogies which also have regenerative braking – one of the intermediate bogie modules is unpowered.

Speed is restricted to 30 mph on-street and 45 mph off-street. The trams have a 100% low floor, 300mm above rail height, throughout. To achieve this, auxiliary equipment is roof mounted and bogies are rigidly fixed to the bogie vehicles with wheels on stub axles which are accommodated under seats together with the longitudinally-fitted traction motors. This arrangement also reduces the cornering squeal as it allows for differential wheel speeds.

Other systems provided onboard the vehicles include CCTV and passenger counting as well as tram detection and positioning.

Testing, Testing, Testing

For weeks prior to service introduction, Edinburgh’s residents have seen empty trams run on their streets. This is part of a rigorous testing and commissioning (T&C) plan which must satisfy a safety verification assessment under the ROGS (Railway and Other Guided Transit Systems) regulations by the Independent Competent Person (ICP) who was appointed in 2007. This early appointment was necessary so that the safety assessment process met the ICP’s requirements.

The route was commissioned in three stages: from the depot at Gogar to the airport in March 2013, then from the depot to Edinburgh Park in December, and finally, in March 2014, from Edinburgh Park to York Place.

After commissioning, a series of system acceptance tests are required to confirm the tram system’s capability. The first of these tests, T1, requires 40 movements by a single tram, 95% of which must be within the target runtime. T1 tests tram priority at junctions and was done at night to minimise the effect of road traffic. The T2 test requires 95% of end-to-end tram movements to meet the required punctuality during three consecutive days of tram operations to the full operational timetable.

T3 is final test before passenger service can be authorised. This requires five consecutive days of the normal timetable and five consecutive days of an enhanced timetable during which a 99% punctuality standard must be achieved. This test also includes confirmation of ride quality.

During this T3 test period, exercises with the emergency services were undertaken which included tram evacuation at various locations, a derailment scenario and crowd management at Murrayfield Stadium. Lessons from these exercises and other aspects of the system acceptance tests were used to refine operational procedures.

Edinburgh joins the club

Edinburgh now has its trams and follows Nottingham (2004), Croydon (2000), Birmingham (1999), Sheffield (1994), Manchester (1992) and Blackpool (1885, modernised 2012) whose tram schemes have proved popular and promoted local economic growth. For example a West Midlands Passenger Transport Executive study indicated that Midland Metro expansion would create around 15,000 jobs and add nearly half a billion pounds to the West Midlands economy.

With the addition of Edinburgh’s 14 km tram network, the UK now has 200km of light rail. This is some way behind France (632 km) and Germany (2,921 km) which clearly believe in the benefits of light rail.

The trams’ advantages would seem to be clear and no doubt Edinburgh’s trams will benefit the city despite their troubled start. Hopefully their comfortable, quiet and pleasant ride should soon ensure that they are as popular as the trams south of the border.